Hi, my last name is also Jimenez and I'm also Jewish. I just recently found out about my history. Same as your grandparents, mine hid their Jewishness but we found it out. Interestingly my dads mom was Ashkenazic from German Jewish roots. Same case as well though. They hid their Jewishness from fear of persecution. It's funny, my I'm very Jewish but only found out when I was about 10yrs old. By the we started going back our roots. I'm very glad to find another Jimenez that is Jewish or at least knows that that they are! Shalom, Akhi!